Why is Tekken 7 doing better in sales than Street Fighter V?

It was revealed in Namco's quarterly summary that Tekken 7s console sales have already exceeded 1.66 million units, with an expectation of 2.1 million units by the end of the year. For reference, Tekken 6 sold 3.5 million over the course of roughly a year and a half. In comparison, Street Fighter V has sold 1.7 million copies as of June across PC and PlayStation 4, however it was supposed to hit 2 million at the end of March 2016. For reference here, the original version of Street Fighter IV sold 3.4 million before the Super version came out the next year.

So if the two are usually neck in neck in sales, why is Tekken 7 outpacing Street Fighter V? Why have Street Fighter V's sales slowed so much?